Electrically conductive stranded wires are frequently terminated with a crimped connection as an alternative to electrical connectors made using soldering, welding, conductive adhesives, and various types of solderless techniques such as insulation displacement, compression, wire clamping and interference fit connections. Crimp connectors are often preferred because they are reliable and inexpensive, easily replaced if damaged, and can provide uniform and reproducible electrical and mechanical characteristics. However, damage to the electrically conductive wires can occur in the immediate vicinity of a crimped connection. This can cause a failure mode that significantly shortens the service life of a crimp connection leading to a failure of a system or vehicle employing the connection. Consequently, it is desirable to reliably and inexpensively evaluate the integrity of a crimped connector.
Another commonly employed technique for determining whether damage has occurred during fabrication of a crimped connector is visual inspection. Unfortunately, visual inspection is not easily employed for small wire diameters or when the crimp connection is not easily accessible, such as when the crimp connector is under a terminal apron or at a junction between a wire and its insulation.
In the installation of a crimped connector, a wire to be terminated is inserted into a terminal sized for the wire gauge that is involved. A tool designed to compress, indent and permanently deform a terminal wall around the wire to form a secure and electrically reliable connection of low resistance is used. At the microscopic level of this junction, asperities of the terminal surface contact the surface of the wire strands, while asperities of the wire strands make contact with the terminal wall. The deformation process keeps a residual stress on the junction to assure that intimate contact between the surfaces is maintained.
In the case of assembly lines where wiring harnesses are manufactured, the equipment is designed for rapid crimp formation. In wiring harness fabrication processes, many connections are made to smaller wire gauges. This requires the use of smaller diameter terminals which must be fabricated with tighter tolerances. The jaws used in the crimped tools are also smaller and are held to tighter tolerances. Therefore, crimping apparatus wear is more problematic and can more quickly and easily lead to degradation in crimp quality. Unfortunately, simple conductivity testing is not a reliable indicator of such degradation and such wear results in a crimp having a greater probability of premature malfunction.